GCC: Variadic ABI (upstreaming)

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Description

Upstreaming and quality assurance efforts of Microsoft variadic function calls ABI implementation.

Dependencies

• None

References

• WIP: Fix function call handling according to Microsoft Arm64 variadic function call ABI gcc-woarm64#37
• WIP: Add tests of Microsoft variadic function call ABI #221

Acceptance Criteria

• The patch series fixing Microsoft ARM64 variadic function calls ABI has been accepted to GCC upstream source code repository.